title: Total hemoglobin concentration in amniotic fluid is increased in intraamniotic infection/inflammation.
abstract: OBJECTIVE
  Discolored amniotic fluid (AF) has been associated with intraamniotic infection/inflammation (IAI) in patients with preterm labor (PTL). The presence of hemoglobin and its catabolic products has been implicated as a cause for AF discoloration. The aim of this study was to determine whether there is an association between total hemoglobin concentration in AF and gestational age, spontaneous labor (term and preterm), and the presence or absence of IAI.
  
  
  METHODS
  This cross-sectional study included patients in the following groups: (1) mid trimester (n = 65 patients); (2) term not in labor (n = 22 patients); (3) term in labor (n = 47 patients); (4) spontaneous PTL who delivered at term (n = 92 patients); (5) PTL without IAI who delivered preterm (n = 76 patients); (6) PTL with IAI (n = 81 patients); (7) preterm prelabor rupture of the membranes (PPROM) with IAI (n = 48 patients); and (8) PPROM without IAI (n = 49 patients). Total hemoglobin concentrations in amniotic fluid were determined by an enzyme-linked immunoassay. Nonparametric statistics were used for analysis.
  
  
  RESULTS
  Hemoglobin was detected in all AF samples (n = 480). The median AF total hemoglobin concentration at term was significantly higher than in mid trimester (520.6 ng/mL [interquartile range (IQR), 271.2-1549.2] vs 58.5 ng/mL [IQR, 26.1-200.8]; P < .001]). Among patients with PTL, the median AF total hemoglobin concentration was significantly higher in patients with IAI than in patients without IAI (4671.7 ng/mL [IQR, 1294.2-8620.7] vs 2013.6 ng/mL [IQR, 629.2-5420.4]; P = .01) or women who delivered at term (1143.4 ng/mL [IQR, 451.8-4037.9]; P = .001). Similarly, among patients with PPROM, the median AF total hemoglobin concentration was significantly higher in patients with IAI than in patients without IAI (10753.7 ng/mL [IQR, 2053.9-56026.6] vs 2281 ng/mL [IQR, 938.2-9191.7]; P = .02). Women at term in labor had a higher median hemoglobin concentration than did women who were not in labor (1952.6 ng/mL [IQR, 709.6-6289.2] vs 520.6 ng/mL [IQR, 271.1-1549.2]; P = .003).
  
  
  CONCLUSIONS
  The AF concentration of immunoreactive total hemoglobin increases with advancing gestational age, and is elevated in pregnancies that are complicated with IAI. Spontaneous labor at term is associated with higher AF concentrations of total hemoglobin.
authors.affiliation: Perinatology Research Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development/National Institutes of Health/Department of Health and Human Services, Bethesda, MD, USA.
authors.forename: Edi
authors.initials: E
authors.lastname: Vaisbuch
authors.forename: Roberto
authors.initials: R
authors.lastname: Romero
authors.forename: Offer
authors.initials: O
authors.lastname: Erez
authors.forename: Juan Pedro
authors.initials: JP
authors.lastname: Kusanovic
authors.forename: Francesca
authors.initials: F
authors.lastname: Gotsch
authors.forename: Nandor G
authors.initials: NG
authors.lastname: Than
authors.forename: Shali
authors.initials: S
authors.lastname: Mazaki-Tovi
authors.forename: Pooja
authors.initials: P
authors.lastname: Mittal
authors.forename: Sam
authors.initials: S
authors.lastname: Edwin
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Hassan
mesh_terms: D000328:Adult; D000653:Amniotic Fluid / Q000737:chemistry*; D023802:Cerclage, Cervical; D002821:Chorioamnionitis / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005322:Premature Rupture of Fetal Membranes / Q000382:microbiology; D005865:Gestational Age; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism; D007752:Obstetric Labor, Premature / Q000378:metabolism / Q000517:prevention & control; D011247:Pregnancy
chemical_list: D006454:Hemoglobins